The present invention relates to a lubricant additive formulation containing no active sulfur, a phosphorus containing compound, multifunctional dispersants in a high viscosity lubricating composition for use in a final drive gearing system.
The wheels of an on-highway and/or off-highway vehicle can be driven by a final drive axle unit that splits the torque received from the input shaft between the wheels by means of a gear set inside a gear housing of the final drive unit. The gears in the final drive can be of the type including but not limited to spiral bevel, hypoid, spur and helical or combination thereof. In one example the gear arrangement can be a differential gear arrangement. These gears require lubrication.
The primary function of the gear lubricant is to provide adequate protection against wear, scuffing and micropitting and provide for seal, rubber and composite material capability, while providing acceptable oxidation stability and cleanliness during the service life of the gear equipment. Therefore, there is need for a gear lubricating composition capable of operating at a higher power throughput and operating temperatures while providing seal, rubber and composite material capability.
U.S. Pat. No. 5,942,470 discloses a gear oil composition containing (i) an oil-soluble sulphur-containing extreme pressure agent or antiwear agent, (ii) at least one oil soluble amine salt of a partial ester of an acid of phosphorus, (iii) a succinimide dispersant with a N—H bond; and (iv) at least one of a nitrogen-containing ashless dispersant, an amine salt of a carboxylic acid and a trihydrocarbyl ester of a pentavalent acid of phosphorus. In one embodiment, the gear oil composition is essentially devoid of any metal-containing additive component.
EP 1191090 discloses a gear oil composition for use in a final drive axle unit containing (i) mineral oil, (ii) vinyl aromatic-diene copolymers, olefin copolymers and mixtures thereof, (iii) at least one polyalphaolefin having a kinematic viscosity of at least 40 mm2/s at 100° C., and (iv) a gear additive package.
The present invention solves the problem of providing a higher viscosity lubricating composition, especially for use in a final drive axle while providing rubber, seal and composite material capability while lubricating gears without the presence of active sulfur in the formulation.